Half Dome picture from some where around Turlock


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Ed Hartouni

Trad climber
Livermore, CA
Dec 22, 2012 - 11:28am PT
here is the Moon rise ephemeris

the apparent altitude is calculated taking into account atmospheric refraction using Saemundson's expression:

R = 1.02/tan((pi/180)*(h+10.3/(h+5.11))/60 (in degrees)

and h is the true altitude (in degrees) the apparent altitude is:

h0 = h + R

[see Meeus p106 eq(16.4)]

that location is "good enough" for altitude... and time.

The Sierra Crest is at an altitude of about 1.2 to 1.5 (estimated from my previous attempt)

The bearings are shown on the map:

the red lines point to Half Dome, the central one at 65 and the upper and lower ones being 0.25 on either side, the angular diameter of the moon is 0.5

the jagged white line is the Half Dome sight boundary, it is visible to the west of that line...

Given the existence of orchards of some sort along the Central Yosemite Hwy. (Hwy 140) it looks like good viewing would be in the field south of the Hwy, and west of Lincoln Rd, though no public roads access the west side of that apparently open field... another option is to go north on Sultana Dr. just a bit south of the aquaduct where there seem to be open fields...

The weather is still wavering for these days... Th is still "partially cloudy" and is worse than the previous Weather Underground report... The NWS calls it "partially sunny" with a chance of rain.

Sunset is around 16:50 for these days.
Stay tuned
Dingus Milktoast

Gym climber
And every fool knows, a dog needs a home, and...
Dec 22, 2012 - 11:35am PT
From a sunnier day in Fed, 09... those vineyards and orchards are pretty. They won't be in bloom yet of course

Good food can be found nearby too.

Good luck! Seems like if the rain don't getchya the fog will. Gotta hope for a wind.
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Dec 22, 2012 - 11:52am PT
Kinda makes it tough to navigate this thread when we get extra-large photos posted. Just saying...
Ed Hartouni

Trad climber
Livermore, CA
Dec 22, 2012 - 11:58am PT
suck it up mouse... tough to read microscopic print at 800x600 pixels...

DMT has his Half Dome shot...

Dec 22, 2012 - 12:54pm PT
Great picture from Mt. Hamilton, Mike. If you get another chance/clear day, and have a red filter (perhaps left over from B+W photography), try also taking long distance photos with the red filter and converting to black and white. Less effect of haze due to scattering and absorption.

I have used a very red filter with a DSLR - you need a tripod because the DSLR is not very sensitive in the red due to an internal IR-blocking filter - to take photos that are almost near-IR. The reduction in haze means the landscape can have an appearance of immense depth. It is an effect that shouldn't be overused, but great for these long distance pictures.
Mike Bolte

Trad climber
Planet Earth
Dec 22, 2012 - 12:56pm PT
Yup - I was up at Mt Hamilton for other business and was luck to have a long lens with me. If I have known what the view was going to be like I would have come better prepared with filters to push the response red and would have tried a few other tricks to increase contrast just in case.

Dec 22, 2012 - 02:55pm PT
Open up your camera and take out the IR filter. I've done this and it is pretty easy with some cameras - practically impossible with others. There are commercial services that do this too. Just google "ir camera conversion."

A red filter on an IR camera would make some cool images.

I converted an old, cheap, point and shoot, digital camera to infrared...
I converted an old, cheap, point and shoot, digital camera to infrared.
Credit: Banquo

Finding an unobstructed view could be an issue. Have you thought about moving across the valley to the hills above I-5? I think Butts Road out of Gustine might work.


The sight distance is about farther (93 miles) which will make a clear picture harder to get.
Ed Hartouni

Trad climber
Livermore, CA
Dec 23, 2012 - 05:07pm PT
Wednesday still has cloud cover and chance of rain...

Thur evening is clearing after that front passes... looking better

Stay tuned... UWa weather model has some good looking isobars happening sometime on Wed... so it is still in the running..
Bruce Morris

Social climber
Belmont, California
Dec 23, 2012 - 05:33pm PT
I think a lot of the critics of the size of Half Dome in this shot ignore that basic fact that the intervening atmosphere acts as a powerful lens enlarging images seen at the horizon. Hence, when you photograph a moon rise, say from Skyline Boulevard, looking east toward Mt Hamilton, the lunar disk, when it first emerges over the horizon, is much larger for a few moments before it ascends higher in the night sky. Sometimes the lunar disk on the horizon even appears at first in discontinuous wider and narrower bands. It seems like this phenomenon is stronger when the intervening atmosphere is more polluted too. Is this due to defraction of the light rays caused by the higher particle count in the atmosphere? Don't know about that, but am sure this shot is the real deal.

Dec 23, 2012 - 10:56pm PT
Bruce, Half Dome looks large because the photographer used a very long telephoto lens and was far away from the barn. Another way of thinking about it is that standing back from the barn made the barn look "small," but standing back a half mile or whatever doesn't change the apparent size of Half Dome much, since it is already many miles away.

Atmospheric refraction is real, but it just bends light, which causes some over-the-horizon and vertical squishing effects (looks like horizontal stretching, a little). It does not magnify objects. The reason that the moon appears larger when near the horizon is an optical illusion, whose origin is not that well understood: http://en.wikipedia.org/wiki/Moon_illusion

Trad climber
from the backseat of Jake& Elwood Blues car
Dec 24, 2012 - 08:06am PT
John I don't know if anyone has posted did read all of them...You can catch Keyes road off highway 99 just past Ceres and just before Turlock. It is posted. You will have to travel east for a while as you make your way out of the urban areas. Years ago I used to be able to catch a glimpse of what I though was Half dome out of my back door right after a good storm. I am about 60 miles away as the crow flies.
Ed Hartouni

Trad climber
Livermore, CA
Dec 24, 2012 - 10:48am PT
the combined effects of atmospheric refraction and the curvature of the Earth highlight the fact
that what we perceive may lead us to conclusions that are very different then what the
"actual" scene presents.

the angular diameters of the Moon and the Sun are roughly 0.5, which is close to the angular
diameter of your thumb held at arms length. The appearance of a "huge moon" on the horizon
can be blotted out by your thumb... (as with the sun at sunset) demonstrating that the actual
angular diameter is not changed significantly.

Atmospheric refraction will change the position of the moon with respect to the horizon, and the
horizon that you view is not the position of the local level of the ground. For instance, if you had
a laser level at the position I was at in the central valley for the shot above, it's "dot" would be
roughly 2000' above sea level in Yosemite (though still below the local surface level). However,
our perception of the Valley, part of which is the perspective we keep in our minds from
familiarity of he place, would seem to suggest that the images produced from the valley were very
different from what we would expect.

In general we do not experience the spherical Earth phenomena, and our perception does not
incorporate it in a scene which it plays an important role... so while most people on this thread
"accept" the theoretical notion that the Earth is a sphere, they would argue passionately that the
view of Half Dome doesn't correspond to their perception of that scene, and therefore the image
is false.

Shades of the inquisition of Galileo...

In some odd way, our perceptual adaptations still dominate our thinking, even though we have
knowledge contrary to those perceptions.

Dec 24, 2012 - 10:56am PT
On Thursday it should be light until 5:21 and the moon rises at 3:48. Looks like a good day if the sky is clear and no fog.

U.S. Naval Observatory
Astronomical Applications Department

Sun and Moon Data for One Day

The following information is provided for Merced, Merced County, California (longitude W120.5, latitude N37.3):

27 December 2012 Pacific Standard Time

Begin civil twilight 6:46 a.m.
Sunrise 7:15 a.m.
Sun transit 12:03 p.m.
Sunset 4:52 p.m.
End civil twilight 5:21 p.m.

Moonrise 3:48 p.m. on preceding day
Moonset 6:31 a.m.
Moonrise 4:39 p.m.
Moon transit 11:58 p.m.
Moonset 7:15 a.m. on following day

Phase of the Moon on 27 December: waxing gibbous with 100% of the Moon's visible disk illuminated.

Full Moon on 28 December 2012 at 2:21 a.m. Pacific Standard Time.

o , o ,
W120 29, N37 18

Altitude and Azimuth of the Moon
Dec 27, 2012
Pacific Standard Time

Time, Altitude, Azimuth

15:45, -9.8, 55.8
16:00, -7.3, 58.3
16:15, -4.9, 60.6
16:30, -2.3, 62.9
16:45, 0.7, 65.1
17:00, 3.1, 67.2
17:15, 5.7, 69.3
17:30, 8.4, 71.4
17:45, 11.1, 73.5
18:00, 13.9, 75.5
Ed Hartouni

Trad climber
Livermore, CA
Dec 24, 2012 - 11:56am PT
check your times... easy to have different definitions depending on how many hours from Greenwich (right now -8)

your table is similar to mine posted above, moon rise is at 4:50pm or so
Ed Hartouni

Trad climber
Livermore, CA
Dec 24, 2012 - 03:23pm PT
seems like Thursday will be clear from noon on...
Wed is chance of showers and cloudy all day long...


Trad climber
Yachats, OR
Dec 24, 2012 - 05:07pm PT
Gonna have to see if I can find that valley shot on one of my drives up the 99.
Half Dome from about 30,000 feet on my way to Oregon.
Half Dome from about 30,000 feet on my way to Oregon.
Credit: BillO
Ed Hartouni

Trad climber
Livermore, CA
Dec 25, 2012 - 02:27pm PT
wed looks dreary, sorta like today...
thu looks less definite, with some cloud cover forecast... but the weather model shows hopeful signs as well as the forecasts

Dec 27, 2012 - 08:51am PT
Current satellite, 1 km VIS:

The United States Naval Observatory (USNO)sun and moon altitude azimuth calculator:

It just might be clear enough in the valley this afternoon.
Ed Hartouni

Trad climber
Livermore, CA
Dec 27, 2012 - 09:35am PT
I'll be there this afternoon/evening to shoot whatever happens...
john hansen

Topic Author's Reply - Dec 27, 2012 - 10:27am PT
Hope you get the shot Ed,, good lick
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